Wireless telecommunication systems are well known in the art. Conventionally, a base station will provide wireless communication for many subscriber units. Base stations will typically handle multiple communications with subscriber systems concurrently. One measure of base station capacity is the maximum number of concurrent communications it can support which is a factor determined by such things as available power and bandwidth.
Since not all subscribers communicate with the base station at the same time, a base station can provide wireless service to a great many subscribers beyond its capacity for concurrent communications. If the maximum number of concurrent communications for a base station are being conducted, an attempt to establish a further communication will result in an indication of service unavailability, such as a system busy signal.
Service coverage by a base station is not only limited to its capacity for handling concurrent communications, but is also inherently limited to a specific geographic area. A base station's geographic range is typically defined by the location of the base station's antenna system and the power of the signal broadcast by the base station.
In order to provide wireless service over an expansive geographic area, a network system is conventionally provided with multiple base stations. Each base station has its antenna system selectively physically located to provide coverage over a specific portion of the total geographic area which is covered by the system. Such systems readily provide wireless service for mobile subscriber units which can travel out of the range of one base station and into the range of another base station without interruption of an ongoing wireless communication. In such networks, the geographic area covered by a base station is commonly referred to as a cell and telephone communication services provide are commonly called cellular telephone services.
Systems constructed in accordance with current specifications of the 3rd Generation Partnership Program (3GPP) are designed to provide such service. In such systems, a typical transmitting base station is known as a “node b” and a typical subscriber unit, mobile or otherwise, is known as a User Equipment (UE).
In designing a telecommunication system to cover a specific geographic area, the geographic area may be partitioned into a predefined pattern of cells. For example as illustrated in FIG. 1A, hexagonal-shape cells can be defined so that the cells cover the entire geographic area in a honeycomb pattern. In such a system, each cell can have a base station which has an antenna at the center of the cell to provide 360° coverage. Although a map of cell coverage may be designed without any overlapping areas, in practice as shown in FIG. 1B, the transmission beams, shown in phantom, from base station antennas of adjacent cells do overlap. This overlap of beam coverage enables “handover” of a communication being conducted by a mobile UE from one base station to another as the mobile UE travels from one cell to another. However, an overlapping base station signal contributes to interference of a signal received by a UE from a different base station when the UE is located in the overlap area.
For a variety of reasons, cells may be defined of various non-uniform shapes. Directional antennas, phased array antennas or other types of antenna systems can be provided so that a beam from a base station antenna for transmission and/or reception covers a particular geographic area of a specific shape and size. As illustrated by base station BS′ in FIG. 1B, the use of directional antennas or phased antenna arrays enables a base station antenna to be located at the edge of a cell in order to provide a shaped beam covering the cell. This can have advantages in better utilization of power and avoidance of creating interference outside the cell, in contrast with merely placing a monopole antenna on the edge of a cell and transmitting a 360° communication beam.
Unlike wireless communication systems which only serve stationary subscriber units, systems designed to communicate with mobile users have much more complex usage patterns since service to a mobile UE can normally be provided by any base station within the system. Accordingly, a particular base station may find its capacity being fully utilized by mobile UEs entering its cell from other cells.
The inventors have recognized that the base station and associated antenna systems may be dynamically used to reconfigure base station transmission and/or reception beams in response to actual use of the wireless system. This can result in dynamically changing overall cell coverage to more readily meet service demands and, thus, better avoid attempted communications being met with a network busy signal. This can also result in “smart” handover to avoid communication degradation when a UE moves from one cell to another.
To implement dynamic beaming forming, the inventors have recognized that data generated by conventional means which identifies the geographic location of a mobile UE, such as using available Global Positioning Satellite (GPS) systems or a base station triangulation technique, can be advantageously used in the dynamic operation of base station antenna systems.